Improving CO photoconversion with ionic liquid and Co single atoms.

Photocatalytic CO conversion promises an ideal route to store solar energy into chemical bonds. However, sluggish electron kinetics and unfavorable product selectivity remain unresolved challenges. Here, an ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate, and borate-anchored Co single atoms were separately loaded on ultrathin g-CN nanosheets. The optimized nanocomposite photocatalyst produces CO and CH from CO and water under UV-vis light irradiation, exhibiting a 42-fold photoactivity enhancement compared with g-CN and nearly 100% selectivity towards CO reduction. Experimental and theoretical results reveal that the ionic liquid extracts electrons and facilitates CO reduction, whereas Co single atoms trap holes and catalyze water oxidation. More importantly, the maximum electron transfer efficiency for CO photoreduction, as measured with in-situ μs-transient absorption spectroscopy, is found to be 35.3%, owing to the combined effect of the ionic liquid and Co single atoms. This work offers a feasible strategy for efficiently converting CO to valuable chemicals.